1. Field
The present disclosure relates generally to aircraft and, in particular, to structures in aircraft. Still more particularly, the present disclosure relates to a composite joint in an aircraft.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than 50 percent of their primary structure made from composite materials. Composite materials are used in an aircraft to decrease the weight of the aircraft. This decreased weight improves performance features, such as, for example, without limitation, payload capacities and fuel efficiencies. Further, composite materials provide longer service life for various components in an aircraft.
Composite materials are tough, light-weight materials, created by combining two or more dissimilar components. For example, a composite material may include fibers and resins. The fibers may be in the form of a substrate or matrix. For example, the fibers may take the form of a woven cloth. The resin may form a reinforcement for the substrate. The fibers and resins are combined and cured to form the composite material.
Further, by using composite materials, portions of an aircraft may be created in larger pieces or sections. For example, a fuselage in an aircraft may be created in cylindrical sections that may be put together to form the fuselage of the aircraft. Other examples of sections that may be put together to form portions of an aircraft include, without limitation, wing sections joined to form a wing, and stabilizer sections joined to form a stabilizer.
In locations where joints are formed using composite materials, some joints may be required to carry higher loads than other joints. For example, joints formed by attaching a wing to a fuselage are examples of joints that are required to carry higher loads.
Composite materials typically have a lower strength when joints are formed by joining composite structures to each other using fasteners. As a result, the composite materials at these types of joints are typically thicker than at other locations. With thicker structures, the size and weight of the fasteners may increase to meet requirements for forming the joint.
The increase in thickness in the composite materials may be undesirable throughout the entire structure. For example, with a skin panel made of composite materials, increasing the thickness of the entire skin panel to allow for a desired thickness for a joint with a fuselage may be undesirable. The increased thickness of the entire skin panel may increase the weight of the aircraft and/or may reduce performance.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.